DESC: UV-C light kills airborne and surface bacteria. Does not produce ozone. Sealed unit design prevents accidental contact with the voltage and with the ultraviolet rays and prevents lamps from lighting unless the base is correctly mounted on the duct. Light viewing window to safely view the lamp operation. SmartLamp Control extends lamp life up to 5 years by optimizing lamp usage depending on fan run-time, or alternatively operates lamps for 3 hours on / 3 hours off. LED blinks to indicate low lamp life, lights solidly when replacement is needed. Power cord plugs into 120 VAC electrical outlet.